Security and alarm systems have been provided through the years in a variety of configurations all directed to protecting a dwelling, office or similar environment against undesired intrusion. Alarm system vary in complexity from relatively simple entry detection systems to extremely complex computer control programmable systems. In many instances, security and alarm systems provide for automatic alert of a remote monitoring station or facility.
The great increase in travel patterns undertaken and exhibited by the population generally through the years has created a substantial need for relatively simple low cost and easily operated and installed alarm systems which are, in essence, portable. Such systems usually rely upon battery power and typically include a master unit together with a mechanically coupled second unit in which the master unit senses the separation or movement of the second unit. In such alarm systems, the basic objective is to detect the relative movement or separation between two window portions or between a door and its surrounding frame or support.
Faced with the need for evermore improved personal or portable alarm systems, practitioners in the art have provided a variety of alarm systems. For example, U.S. Pat. No. 882,570 issued to Liaci sets forth a BURGLAR ALARM having an electric circuit, a movable spring controlled contact device within the circuit, connections between the contact device and the point to be protected for actuating the contacts against a resisting spring to close the contact circuit in the event the connections are separated by the movement of the to-be-protected point.
U.S. Pat. No. 4,149,156 issued to Blasucci sets forth a WINDOW ALARM EMPLOYING A RELEASABLY MOUNTED PLUNGER SWITCH in which a plunger switch is releasibly held against the inner surface of the outer section of a double hung window or sliding door by a suction cup. Movement of the inner section with respect to the outer section of the door or window dislodges the suction cup releasing the spring-biased switch therein permitting it to close. The switch is coupled to signaling means which generate an alarm signal upon switch closure.
U.S. Pat. No. 4,205,305 issued to Nakada sets forth a BURGLAR ALARM having a housing which contains a bell assembly and battery compartment connected in series with a switch assembly having a linearly movable element which is displaceable a predetermined threshold distance by a chain extending to a magnet temporarily joined to a metal jacket attached to a movable surface. The switch assembly contains a pivoted contact which moves against a fixed contact when the linearly movable element is displaced a predetermined distance.
U.S. Pat. No. 4,206,452 issued to Blasucci sets forth a TENSION CORD BURGLAR ALARM having a plurality of members attachable to a window or door around which a cord is stretched under tension in the form of a polygon. A switch is positioned within the polygon such that the switch is attached by further cords to two sides of the polygon. The switch is held under a selected tension and the shape of the polygon is such that an intruder cannot enter through the window or door without disturbing the cord polygon and thereby the tension in the switch. The switch is designed to respond to a change in tension applied thereto and to supply a signal to an alarm system.
U.S. Pat. No. 4,222,042 issued to Cantley sets forth a DOOR ALARM which is mounted on the inside of a door adjacent to the hinged edge thereof. The alarm includes a housing having a buzzer and battery power system supported therein. An arming lever is pivotally mounted to the housing and extends outwardly therefrom operatively engaging an actuator block mounted on the door frame adjacent the housing. The lever and conductor are operatively connected to the battery and buzzer to form an alarm circuit which will actuate the buzzer when the door is opened.
U.S. Pat. No. 4,284,982 issued to Downey sets forth a BATTERY-OPERATED PERSONAL ALARM having a withdrawable actuating pin extending from the case thereof. A multi-purpose handle attached to the exterior of the case permits attachment of the alarm to a purse handle or the like in a first position. In a second position, the handle permits attachment of the alarm to a door handle for use as a portable burglar alarm. Removable of the handle from its inverted keyhole shaped aperture on the back of the case permits hanging the alarm from a screw head or nail attached to a fixed support.
U.S. Pat. No. 4,292,629 issued to Kerr, et al. sets forth an ALARM SYSTEM intended to signal an attempted intrusion through an opening frame having movable panels therein. An electrical switch mounted upon one panel has an element responsive to a magnetic field for developing a signal. A magnet mounted on the other panel is productive of a magnetic field which interacts with the element of the switch upon movement between the panels. A signaling device is coupled to the switch and produces an alarm indication when movement is sensed
U.S. Pat. No. 4,533,904 issued to Steinman, Jr. sets forth a COMBINATION SMOKE AND BURGLAR ALARM having a housing adapted for mounting on an interior room surface such as a wall or ceiling above a door or window. A releasibly inserted locking pin retains a spring-biased plunger mounted above a pressure actuatable tester switch accessible externally of the housing to maintain the plunger in its cocked condition. A line attached to the releasible pin also attaches to an adjacent door or window such that opening of the door or window increases tension on the line removing the locking pin and releasing the plunger to strike the tester button and actuate the alarm.
While the foregoing described prior art devices have provided some measure of success in providing portable alarm systems, there remains nonetheless a continuing need in the art for evermore improved low cost compactly designed and reliable portable alarm systems.